There exists a display device which reads out image data written in a frame memory and transfers the image data thus read out to a display panel such as an LCD (Liquid Crystal Display). In a case where image data is transferred from a host processor (hereinafter referred to simply as “host”) to the display panel such as the LCD, the image data is typically first stored temporarily in the frame memory of an LCDC (LCD Controller), and is then outputted to the display panel. Accordingly, while the image is not changed, transfer of image data from the host to the frame memory can be stopped, and display on the display panel can continue to be carried out with use of the image data which is already stored in the frame memory.
However, in a case where a process of writing image data into the memory and a process of reading out the image data from the memory are carried out substantially simultaneously in the display device having the above-described arrangement, one of the writing process and the reading process may overtake the other while the other is still being carried out, due to, for example, a difference in speed between the writing process and the reading process. In this case, image data that is read before the overtaking is different from image data that is read after the overtaking. As a result, image data outputted to the display panel may contain both a portion of the image which was read before the overtaking and a portion of the image which was read after the overtaking.
Patent Literature 1 discloses a frame rate changing device which temporarily stops writing in a case where the frame rate changing device determines that overtaking between writing and reading will occur.